Spidermites (Tetranychus urticae) are one of the most common insect pests. Spidermites are the direct cause of millions of dollars in damage per year to a wide variety of plant types. Spidermites generally attach themselves to the leaves of a plant and suck the moisture out of plant foliage. Spidermites will stunt or wilt new plant growth and, in severe infestations, may kill the host plant. Spidermites are particularly damaging to plants that are already subject to heat or drought-related stress.
Predatory mites feed on spidermite eggs and adult spidermites, and are one means of controlling spidermite populations. Predatory mites are particularly popular with organic growers seeking non-chemical biological pest control agents. The predatory mites are generally quicker and more agile (although not necessarily larger) than the spidermites that they prey on, and they can seek out prey in areas that may be missed or are inaccessible to perfunctory chemical sprays. Additionally, unlike chemical sprays, spidermites cannot develop a tolerance or immunity to predatory mites. Predatory mites may also be used against several species of thrips.
Predatory mites are a particularly successful pest control agent in greenhouses because of the high degree of control that the grower has over the greenhouse environment. The most prolific and effective types of predatory mites function best in a specific temperature and humidity envelope. However, several predatory mite species are successfully used to suppress spidermites in non-greenhouse environments on crops such as apples, citrus, and avocados as well as strawberries and raspberries.
In the preferred embodiment, the current invention is directed to producing the predatory mite Phytoseiulus persimili. However, the invention may also be used to produce a variety of other mites and insects. For the purposes of this patent specification, the term “predatory mites” will be used to generally refer to any mite species that feeds on other arthropods.
Predatory mites are currently produced and marketed by several commercial organizations. An index of beneficial insect producers (including predatory mite producers) is available from www.bugladyconsulting.com/Suppliers%21of %21beneficial%21insects.htm.
Most predatory mite production is currently done in greenhouses in an essentially uncontrolled manner. Predatory mites are simply deposited on vegetation that is infested with spidermites and left for a pre-determined amount of time. Workers then harvest the predatory mites remaining in the vegetation. Strict protocols (and generally separate greenhouses) are required to keep the predatory mites separate from the spidermites until a specifically prescribed stage in the production process. The prior art process is not continuous and one cycle requires about six weeks from start to harvest.
While the prior art method is simple, it is also relatively labor-intensive and inefficient, and it results in inconsistent harvests. Further, there is always a significant time gap between the start of the predatory mite production process and the window in which the mites can be harvested.
The need exist for a systematic means of continuously feeding and harvesting predatory mites so that good quality predatory mites are produced. The current invention provides an enclosed, modular, and systematic means of continuously producing healthy predatory mites. Once the system is up and running, maintaining the system requires minimal operator skill and knowledge and enables the operator to produce predatory mites for an essentially indefinite period of time. In laboratory tests, the process of the current invention has been shown to increase predatory mite production by 21-300% relative to prior art processes involving similar time periods and similar resources.